I have seen beginners try it in faux blackwater with bad results. The light situation is the problem. As you most often only get it in-vitro, the stuff is very short when you buy it, thus planted it in the substrate it will rot away "in the dark". I have seen people grow it semi-emersed on moss patches on emersed driftwood, though. No idea if it really can make it with the water parameters. It always seems to be a popular plant in Aquascaping with quite demanding plants. Those are typically out for blackwater setups.Question: WIll pearl weed grow in blackwater ?